Mechanical joint for an orthopedic brace or prosthesis

ABSTRACT

A mechanical joint for a leg brace having portions attachable to the leg above and below the knee joint and interconnected by a link. The spaced ends of the brace portions and the opposite ends of the link are shaped to provide bearing plates which are secured together by movable pivot means. This provides the mechanical joint with dual bearings having a combined pivotal movement closely simulating the flexing action of an anatomical knee.

ilnited States Patent [191 Taylor Sept. 2, 1975 [54] MECHANICAL JOINTFOR AN 1,336,695 4/1920 Gromes 128/88 ORTHOPEDIC BRACE OR PROSTHESIS3,799,158 3/1974 Gardner 128/80 C Inventor: George A. Taylor, 976Saunders Rd., Richmond, British Columbia, Canada, V7a 2134 Filed: May28, 1974 Appl. No.: 474,133

Foreign Application Priority Data May 21, 1974 Canada 200442 US. Cl.128/80 F; 3/22; 3/26; 403/95; 403/116; 128/88 Int. Cl A61f 5/00; A6lf1/04 Field of Search 128/80 F, 80 C, 80 R, 88; 3/22, 24, 26, 27; 403/95,116, 119, 113

References Cited UNITED STATES PATENTS 12/1895 Rankin .l 128/80 FFOREIGN PATENTS OR APPLICATIONS 826,333 12/1951 Germany PrimaryExaminerR0nald L. [Frinks Attorney, Agent, or F irmFetherstonhaugh & Co.

57 ABSTRACT A mechanical joint for a leg brace having portionsattachable to the leg above and below the knee joint and interconnectedby a link. The spaced ends of the brace portions and the opposite endsof the link are shaped to provide bearing plates which are securedtogether by movable pivot means. This provides the mechanical joint withdual bearings having a combined pivotal movement closely simulating theflexing action of an anatomical knee.

9 Claims, 13 Drawing Figures PATEN IEB SEP 2 I975 SHiEI 1 BF 3 PATENTED975 SHEET 2 0F 3 MECHANICAL JOINT FOR AN ORTHOPEDIC BRACE OR PROSTHESISMy invention relates generally to joints for orthope-. dic braces orprosthetics and more particularlyto a mechanical joint for a leg brace.

When a brace is worn to lend support to an injured or weakened knee, itis generally desirable that the properly supported limb be allowed tooperate in as natural a manner as possible so that appropriate musclesand ligaments will become strengthened and eventually the support willno longer be required. Even if the injury or weakness is permanent, thebrace wearer should not be hampered unduly by the device so that hisinability to use his leg in a normal manner is more noticeable thanwould otherwise be the case.

A leg brace requires a mechanical joint which will take some ofamedially or laterally applied load off the knee joint but the mechanicaljoint itself should not be heavy, bulky or complex otherwise the braceis awkward to wear and is noticeable through the wearers clothing and isneedlessly expensive. There are a number of artificial limbs which havemechanical joints designed to reproduce as closely as possible theflexing action of the human knee but such joints usually are of quitecomplex construction and furthermore they occupy a major portion of thespace between the upper and lower parts of the artificial leg. Thisarrangement is unsatisfactory for use in a leg brace wherein the jointstructure must lie alongside the anatomical knee joint and be flat andcompact so as not to provide an unsightly projection sticking out fromone side of wearers leg.

I have found that the above mentioned as well as other disadvantages ofconventional hinge structures can be overcome by providing a simply andinexpensively constructed brace with a mechanical joint which isdesigned to reproduce very closely the natural movements of a bodyjoint. The mechanical joint is light in weight as well as strong and ithas an overall thickness which is not much greater than the remainder ofthe brace which makes the device difficult to detect through theclothing of the wearer. An athlete, for example, who might have a kneeinjury such as a strained ligament, could wear the present invention toprotect the knee from severe blows or stress which could quite easilyfurther damage the knee and incapacitate him completely.

The mechanical joint for an orthopedic brace con structed in accordancewith the present invention interconnects brace portions which areattachable to parts of a wearers body on opposite sides of a body joint,the mechanical joint comprising a bearing plate on an end of each braceportion near the body joint, a link extending across the body joint andhaving a bearing plate on each opposite end thereof, said bearing platesof the link overlapping the bearing plates of the brace portions toprovide dual bearings, and pivot means inter connecting the bearingplates of each of the dual bearings, said pivot means providing the dualbearings with transverse axes of pivot which are shiftable whereby thelink is movable away from and towards the brace portions as the bodyjoint is flexed and straightened.

In drawings which illustrate preferred embodiments of the invention,

FIG. 1 is a side elevation of a leg brace,

FIG. 2 is a detail side elevation of a mechanical joint of the legbrace,

FIG. 3 is a side elevation of a link which forms part of the mechanicaljoint,

FIG. 4 is a section taken on the line 4-4 of FIG. 3,

FIGS is a vertical section showing a bearing plate of the mechanicaljoint,

FIG. 6 is a transverse section taken on the line 66 of FIG. 2

FIG. 7 is a transverse section taken on the line 7-7 of FIG. 2, i

. FIG. 8 is a vertical section taken on the line 8-8 of FIG. 2,

FIG. 9 is a side elevation similar to FIG. 1 but showing the mechanicaljoint bent as a result of the wearers knee being flexed,

FIG. 10 is a rear elevation of the mechanical joint as shown in FIG. 9,

FIG. 11 is a perspective view of a modified mechanical joint for a legbrace,

FIG. 12 is a detail side elevation of the modified joint with part of alink removed, and

FIG. 13 is a transverse section taken on the line 1313 of FIG. 12.

This invention may be used to reinforce anatomical joints such as theshoulder, elbow, hip and ankle but, since the brace is especiallydesigned to simulate the gliding, rocking and rotational movement of thehuman knee, it will be described herein as utilized exclusively for thatpurpose. A persons knee can be likened to a ball and socket joint havinga rather unusual action for that type of mechanism. When the knee bendsand straightens during walking or running, the ball of the upper leg andsocket of the lower leg interact in such a way as to move away from andtowards one another. The leg actually extends and contracts duringlocomotion and, when the parts of the knee joint are separated, thelower leg can twist slightly with respect to the upper leg. It is onlywhen the leg is straightened and supporting the weight of the body thatthe knee joint is locked and the lower leg cannot twist as described.Thus, the natural knee joint has a point of pivot which moves about asthe leg is alternately bent and straightened with the knee providing arestricted universal action unless firmly locked as described.

Referring first to FIG. 1 of the drawings, the numeral 10 indicatesgenerally an orthopedic leg brace. The brace 10 is shown attached to aleg 12 so as to lend support to the knee joint 14. This example of thebrace 10 has a lower portion 15 which is a flat strip of metal shaped toextend alongside lower leg 16 with one end of .the portion preferablybeing secured by a fitting 17 to the shoe of the wearer. Upper portion20 of the brace is also a flat strip of suitably shaped metal which issecured to a stiffened leather band 21, the longitudinally divided bandbeing clamped to the thigh 22 of the wearer by means of straps 23. Theadjacent ends of the brace portions 15 and 20 are connected by amechanical joint generally indicated at 24, the joint being disposedalongside the knee joint 14 when the brace 10 is attached to the wearersleg as described.

The mechanical joint 24 comprises bearings 26 and 28 (FIG. 2) whichpivotally connect the brace portions 15 and 20 to a link 30. The link 30is shown separately in FIGS. 3 and 4 asbeing shaped to providesubstantially circular bearing plates 32 and 33. A flat web 34 extendsbetween the plates 32 and 33 along the front edge of the link. Plate 32has an inner concave face 36 and an outer convex face 37. The outerconvex face 37 is coated with a suitable plastic anti-friction materialand preferably this coating 38 is the syntheticmaterial known by thetrade mark Teflon. Similarly, the bearing plate 33 has a concave face 40and a convex face 41 with the latter face having a plastic coating 42.-

The lower portion of the brace is provided with a bearing plate 45, seeparticularly FIGS. 2 and 5, which plate overlaps and closely fits thebearing plate 32 of the link thereby forming the bearing 26. Preferably,the bearing plate 45 is formed by a stamping process which shapes theupper end of the metal brace portion 15 into a dished configuration thusproviding a concave inner face 46 and a convex outer face 47, see FIG.5. Firmly bonded to the face 46 is a thin plastic coating 48. Thus, theplastic coated faces 37 and 46 when placed in sliding contact with oneanother provide the bearing 26 with a particularly smooth action whichenables the brace portion 15 to rock on the link 30 in severaldirections.

Referring now particularly to FIGS. 2 and 6, the upper portion of theleg brace will be seen to be shaped to provide a bearing plate 50 havingconcave and convex inner and outer faces 51 and 52. Face 51 has aplastic coating 53 which serves as anti-friction material. The plasticcoated face 51 fits over the underlapping and similarly coated face 41of the link so that the bearing 28 has an action similar to the actionof the bearing 26 whereby said link can move relative to the braceportion 20 again in a number of different directions.

The plates 32 and 45 of the bearing 26 are held in face-to-face slidingcontact by pivot means generally indicated at 60. As shown best in FIGS.2, 3, 6 and 9 of the drawings, the means 60 comprises pivot pins 62 and63 which are suitably secured to the plate 32 to project outwardly fromthe convex face 37. These pivot pins, which have short shanks andflattened heads, are located on opposite sides of the center of thesubstantially circular bearing plate 32 as can best be seen in FIG. 3.Bearing plate 45 is provided with arcuate guide slots 64 and 65, seeparticularly FIG. 2. The shank of the pivot pin 62 projects freelythrough the slot 64 and the shank of the pivot pin 63 similarly projectsthrough the relatively long guide slot 65 with the enlarged heads ofthese pins slidably engaging the outer or convex face 47 of the bearingplate 45 to hold these two parts of the bearing 26 against separation.

A similar pivot means 70 is provided to interconnect the plates 33 and50 of the bearing 28. The means 70 comprises identical pivot pins 72 and73 which are secured to the plate 33. Arcuate guide slots 74 and 75 areformed in the bearing plate 50, see FIG. 2, and the short shanks of thepins 72v and 73 project freely through these slots with the heads ofsaid pins slidably engaging the convex face 52 of the plate to hold thebearing 28 against separation.

The mechanical joint 24 includes stop means generally indicated at 80for limiting swinging movement of the lower brace portion beyond theposition assumed thereby when the wearers leg is straightened and theupper and lower brace portions are substantially aligned. Referring nowparticularly to FIG. 2, the means 80 is shown to comprise opposing stops82 and 83 which are flattened end edges of the bearing plates 45 and 50respectively. These stops 82 and 83 come into contact with one anotherwhen the leg 11 is straight and the knee 14 is locked. At this time, theshanks of the pivot pins 62 and 63 are in contact with the opposite endsof the guide slots 64 and 65. The pins 72 and 73 are similarlypositioned in their slots 74 and 75. The upper and lower portions 15 and20 are substantially aligned when the leg 11 is straight and it is atthis alignment that the stop means comes into play to halt furtherbending movement of the mechanical joint 24 which might impose a strainon the locked knee 14. In other words, the stops 82 and 83 cooperatewith the arrangement of pivot pins and slots to limit swinging movementof the brace portions 15 and 20 beyond their substantially alignedpositions.

The present joint 24 also includes locking means generally indicated bythe numeral for securing the bearing plates of the dual bearings againstrelative movement when the upper and lower brace portions are in thesubstantially aligned position. Referring to FIGS. 2, 7 and 8, the means90 is shown to comprise a flap 92 which extends across the center of thelink 30. A hinge 93 secures one end of the flap 92 to the web 34 of thelink. In FIG. 7, a small spring 94 will be seen incorporated into thehinge 93 to bias the flap 92 away from the link, and said flap is fittedwith a lug 95 which contacts the web 34 to limit outward swingingmovement of the flap. The flap 92 is provided with spaced dowels 96 and97 which are adapted to enter holes 98 and 99 formed in the link 30 toregister with the ends of the slots 65 and 75 when he mechanical joint24 is in the FIG. 2 position.

Normally, the flap 92 is held in the FIG. 7 position by the action ofthe spring 94 and lug 95 at which time the dowels 96 and 97 aresupported clear of the bearing plates 45 and 50. The joint 24 is thenfree to operate as required. At some time the wearer of the brace 10might decide to lock the joint 24 so that his knee could no longer beflexed and, in order to do so, he would first straighten the leg to thelimit determined by the stop means 80. This places the holes 98 and 99in register with the dowels 96 and 97 whereupon the flap 92 can bepressed inwardly to project the dowels through the slots 65 and 75 andinto said holes where they are held by friction. The joint 24 is thenlooked and cannot be released until the flap 92 is moved manually to theFIG. 7 position.

The operation of the mechanical joint 24 is best understood withreference to FIGS. 9 and 10. When the lower leg 16 swings to the rear asthe wearer of the brace 10 walks. the joint 24 performs a hinging actionwhich closely simulates the flexing action of the knee 14. The severalpivot pins of the bearings 26 and 28 allow the link 30 and brace portion15 to swing relative to the brace position 20 but. since these pins arefree to move as required within their arcuate slots, the effect is toprovide the joint with a plurality of transverse axes of pivot. In otherwords, the mechanical joint can elongate slightly in the same manner asdoes the knee joint when it is flexed.

Since the several plates of the bearings 26 and 28 are segment of athin-walled, hollow spheroid. the link 30 and brace portion 15 can alsorotate slightly about their longitudinal axes to assume positionssubstantially as shown in FIG. 10. This allows the wearer to turn hislower leg when the knee 14 is flexed as he may be required to do inorder to execute a particular step. The mechanical joint allows the kneejoint to function in a natural manner while being supported to theextent that any undue strain is unlikely to be placed thereon.

Referring to FIGS. 11, 12 and 13; the numeral 110 indicates generally amodified mechanical joint for a leg brace having portions 112 and 114.The brace portion 112 has a flat bearing plate 116, see FIG. 12,provided with arcuate guide slots 117 and 118. Brace portion 114 has asimilar flattened bearing plate 120 in which arcuate slots 121 and 122(FIG. 12) are formed.

A link 124, which is also flat as shown best in FIG. 13, has bearingplates 125 and 126 which overlap the plates 116 and 120 of the braceportions. Pivot pins 130, 131, 132 and 133 are carried by the link 124to slidably project through the slots 117, 118 121 and 122 respectively.A cover 135 of substantially the same shape as the link 124 extends overthe bearing plates 116 and 120, the cover being secured to the link theaforesaid pivot pins which are riveted over as shown in FIG. 11.

The above described arrangement provides the mechanical joint 110 withdual bearings which are generally indicated at 137 and 138. Since thesedual bearings are formed with flattened bearing plates, they allow thebrace portions 112 and 114 to hinge or fold in a substantially commonplane but, of course, one position cannot twist with respect to theother portion as is the case when dished or concave-convex bearingplates are used. The pivot pins 130 to 133 are still received in arcuateslots so that the resulting pivot means provides a plurality oftransverse axes of rotation for the mechanical joint 110. Such a jointis particularly intended for use by paraplegics and others who mightfind it easier to get around provided their legs were reinforced bybraces fitted with the modified joint.

The joint 110 has stop means and locking means which are generallyindicated by the numerals 140 and 141 respectively. Since these twomeans are constructed substantially as their counterparts 80 and 90 ofthe main embodiment of the invention, and operate in almost the samemanner, detailed description of the two devices is not considerednecessary.

From the foregoing, it will be apparent I have provided a mechanicaljoint for a leg brace which is simply yet sturdily constructed withoutbeing heavy or bulky. The knee joint is not restricted in its movementany more than is necessary to provide the required support and thereforethe wearer can walk and run with quite a natural gate assuming the bracehe is wearing is equipped with the preferred mechanical joint. Bothembodiments of the invention provide a joint which might be described aspolyaxial, viz. there is no fixed axis of pivot but rather a multitudeof pivotal axes which move about or shift as required to accommodate thenatural flexing action of the anatomical knee joint.

I claim:

1. In an orthopedic brace having portions attachable to parts of awearers body on opposite sides of a body joint, a mechanical jointcomprising a bearing plate on an end of each brace portion near the bodyjoint, a link extending across the body joint and having a bearing plateon each opposite end thereof, said bearing plates of the linkoverlapping the bearing plates of the brace portions to provide dualbearings, and pivot means interconnecting the bearing plates of each ofthe dual bearings, said pivot means providing each of the dual bearingswith a plurality of transverse axes of pivot which are shiftable toaccommodate the natural pivotal movement of the body joint whereby oneof said brace portions is movable away from and towards the other ofsaid brace portions as the body joint is flexed and straightened. I

2. Ajoint as claimed in claim ll, in which said bearing plate of each ofthe dual bearings have opposing concave-convex faces whereby one of thebrace portions is rotatable about the longitudinal axis thereof and withrespect to the other brace portion and the link when the body joint isflexed.

3. A joint as claimed in claim 1, and including stop means for limitingfolding movement of the mechanical joint in one direction beyond aposition assumed when the body joint substantially is straight.

4. Ajoint as claimed in claim 3, and including locking means forsecuring the mechanical joint against folding movement in the oppositedirection.

5. Ajoint as claimed in claim 1, in which said bearing plates are flatwhereby to move parallel to one another and substantially in thevertical planes of the brace portions.

6. In an orthopedic brace having upper and lower brace portionssecurable to a leg above and below the knee joint, a mechanical jointcomprising a bearing plate on each of the upper and lower brace portionsnear the point of pivot of the knee joint, a link extending across theknee joint and having a bearing plate overlapping a bearing plate ofeach upper and lower brace portions to provide dual bearings, saidbearing plates having opposing faces, one opposing face of each of thedual bearings being convex and the other opposing face of said bearingbeing concave, one bearing plate of each of the dual bearings havingpivot pins spaced apart thereon and the other bearing plate of saidjoint having correspondingly spaced arcuate guide slots through whichsaid pivot pins project, said pivot pins and arcuate guide slotsproviding each of the dual bearings with a plurality of transverse axesof pivot which are shiftable to accommodate the natural pivotal movementof the knee joint and whereby the link and the lower brace portion arerotatably about their longitudinal axes and are movable away from theupper brace member when the knee joint is flexed.

7. A mechanical joint as claimed in claim 6, and including stop meansfor limiting swinging movement of the lower brace portion beyond theposition assumed thereby when the wearers leg is straightened and theupper and lower brace portions are substantially aligned.

8. A mechanical joint as claimed in claim 7, and including locking meansfor securing the bearing plates of the dual bearings against relativemovement when the upper and lower brace portions are in thesubstantially aligned position.

9. A mechanical joint as claimed in claim 8, wherein said locking meanscomprises a hinged flap carried by the link, said bearing plates of theupper and lower brace portions each haaving a hole adapted to registerwith a guide slot when said portions are substantially aligned, anddowels carried by the hinged flap adapted to project through theregistering guide slots to enter the holes.

1. In an orthopedic brace having portions attachable to parts of awearer''s body on opposite sides of a body joint, a mechanical jointcomprising a bearing plate on an end of each brace portion near the bodyjoint, a link extending across the body joint and having a bearing plateon each opposite end thereof, said bearing plates of the linkoverlapping the bearing plates of the brace portions to provide dualbearings, and pivot means interconnecting the bearing plates of each ofthe dual bearings, said pivot means providing each of the dual bearingswith a plurality of transverse axes of pivot which are shiftable toaccommodate the natural pivotal movement of the body joint whereby oneof said brace portions is movable away from and towards the other ofsaid brace portions as the body joint is flexed and straightened.
 2. Ajoint as claimed in claim 1, in which said bearing plate of each of thedual bearings have opposing concave-convex faces whereby one of thebrace portions is rotatable about the longitudinal axis thereof and withrespect to the other brace portion and the link when the body joint isflexed.
 3. A joint as claimed in claim 1, and including stop means forlimiting folding movement of the mechanical joint in one directionbeyond a position assumed when the body joint substantially is straight.4. A joint as claimed in claim 3, and including locking means forsecuring the mechanical joint against folding movement in the oppositedirection.
 5. A joint as claimed in claim 1, in which said bearingplates are flat whereby to move parallel to one another andsubstantially in the vertical planes of the brace portions.
 6. In anorthopedic brace having upper and lower brace portions securable to aleg above and below the knee joint, a mechanical joint comprising abearing plate on each of the upper and lower brace portions near thepoint of pivot of the knee joint, a link extending across the knee jointand having a bearing plate overlapping a bearing plate of each upper andlower brace portions to provide dual bearings, said bearing plateshaving opposing faces, one opposing face of each of the dual bearingsbeing convex and the other opposing face of said bearing being concave,one bearing plate of each of the dual bearings having pivot pins spacedapart thereon and the other bearing plate of said joint havingcorrespondingly spaced arcuate guide slots through which said pivot pinsproject, said pivot pins and arcuate guide slots providing each of thedual bearings with a plurality of transverse axes of pivot which areshiftable to accommodate the natural pivotal movement of the knee jointand whereby the link and the lower brace portion are rotatably abouttheir longitudinal axes and are movable away from the upper brace memberwhen the knee joint is flexed.
 7. A mechanical joint as claimed in claim6, and including stop means for limiting swinging movement of the lowerbrace portion beyond the position assumed thereby when the wearer''s legis straightened and the upper and lower brace portions are substantiallyaligned.
 8. A mechanical joint as claimed in claim 7, and includinglocking means for securing the bearing plates of the dual bearingsagainst relative movement when the upper and lower brace portions are inthe substantially aligned position.
 9. A mechanical joint as claimed inclaim 8, wherein said locking means comprises a hinged flap carried bythe link, said bearing plates of the upper and lower brace portions eachhaaving a hole adapted to register with a guide slot when said portionsare substantially aligned, and dowels carried by the hinged flap adaptedto project through the registering guide slots to enter the holes.